I made this today for my daughters craft table. Plastic Ikea cups screwed to a lazy susan. It works a treat ! The more organised you are, the more productive and professional you will be with your work, and it's great to introduce this method of working at an early age. I always make sure my children have a range of good quality art materials to work with. They have sharpened pencils, felt tip textas that work and wind up crayons for achieving details. If anything doesn't work I toss it out, rummaging around to look for something wastes time and blocks the creative process. In the centre of the lazy-susan I have placed a large tin full of grey leads and writing pens. They also have a separate container for scissors, staplers, rulers, sticky tape, paperclips, erasers etc.
Setting up functional work space for your children will help them feel enthusiastic and confident with their artwork. The same goes for all of us actually !.